README.md

layout	title	permalink
quickstart-optics	Optics	/optics/

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Arrow Optics. Transforming and computing over immutable data models in Kotlin

Arrow Optics provides an automatic DSL that allows users to use . notation when accessing, composing, and transforming deeply nested immutable data structures.

Optics also offers all the base types such as [Lens]({{ "/optics/lens/" | relative_url }}), [Prism]( {{ '/optics/prism/' | relative_url }}), and others from which we can generalize accessing and traversing deep values in sealed and data classes models.s

## Arrow Optics Overview

#### Quick Start - [Gradle Setup]({{ '/optics/#Gradle-kotlin' | relative_url }}) - [Maven Setup]({{ '/optics/#Maven' | relative_url }})

#### DSL - [Optics DSL]({{ '/optics/dsl/' | relative_url }})

#### Extensions and data types - [Iso]({{ '/optics/iso/' | relative_url }}) - [Lens]({{ '/optics/lens/' | relative_url }}) - [Optional]({{ '/optics/optional/' | relative_url }}) - [Prism]({{ '/optics/prims/' | relative_url }}) - [Getter]({{ '/optics/getter/' | relative_url }}) - [Setter]({{ '/optics/setter/' | relative_url }}) - [Fold]({{ '/optics/fold/' | relative_url }}) - [Traversal]({{ '/optics/traversal/' | relative_url }}) - [Every]({{ '/optics/every/' | relative_url }}) - [Cons]({{ '/optics/cons/' | relative_url }}) - [Snoc]({{ '/optics/snoc/' | relative_url }}) - [At]({{ '/optics/at/' | relative_url }}) - [Index]({{ '/optics/index/' | relative_url }}) - [FilterIndex]({{ '/optics/filterindex/' | relative_url }})

#### Additional information - [Kotlin Data classes](https://kotlinlang.org/docs/data-classes.html) - [Kotlin Sealed classes](https://kotlinlang.org/docs/sealed-classes.html)

## Setup

{: .setup-subtitle} Configure Arrow for your project

![Jdk]({{ "/img/quickstart/jdk-logo.svg" | relative_url }} "jdk")

Make sure to have the latest version of JDK 1.8 installed.

![Android]({{ "/img/quickstart/android-logo.svg" | relative_url }} "android")

Arrow supports Android starting on API 21 and up.

Gradle Kotlin DSL Gradle Groovy DSL Maven

Basic Setup

In your project's root build.gradle.kts, append this repository to your list:

allprojects {
    repositories {
        mavenCentral()
    }
}

Add the dependencies into the project's build.gradle.kts:

apply plugin: 'kotlin-kapt'

dependencies {
    implementation("io.arrow-kt:arrow-optics:1.0.1")
    kapt("io.arrow-kt:arrow-meta:1.0.1")
}

BOM file

To avoid specifying the Arrow version for every dependency, a BOM file is available:

dependencies {
    implementation(platform("io.arrow-kt:arrow-stack:1.0.1"))

    implementation("io.arrow-kt:arrow-core")
    implementation("io.arrow-kt:arrow-optics")
    ...
}

Next development version

If you want to try the latest features, replace 1.0.1 with 1.0.2-SNAPSHOT and add this configuration:

allprojects {
    repositories {
        ...
        maven(url = "https://oss.sonatype.org/content/repositories/snapshots/")
    }

    // To use latest artifacts
    configurations.all { resolutionStrategy.cacheChangingModulesFor(0, "seconds") }
}

Basic Setup

In your project's root build.gradle, append this repository to your list:

allprojects {
    repositories {
        mavenCentral()
    }
}

Add the dependencies into the project's build.gradle:

apply plugin: 'kotlin-kapt'

def arrow_version = "1.0.1"
dependencies {
    implementation "io.arrow-kt:arrow-optics:$arrow_version"
    kapt    "io.arrow-kt:arrow-meta:$arrow_version"
}

BOM file

To avoid specifying the Arrow version for every dependency, a BOM file is available:

def arrow_version = "1.0.1"
dependencies {
    implementation platform("io.arrow-kt:arrow-stack:$arrow_version")

    implementation "io.arrow-kt:arrow-core"
    implementation "io.arrow-kt:arrow-optics"
    ...
}

Next development version

If you want to try the latest features, replace 1.0.1 with 1.0.2-SNAPSHOT and add this configuration:

allprojects {
    repositories {
        ...
        maven { url "https://oss.sonatype.org/content/repositories/snapshots/" }
    }

    // To use latest artifacts
    configurations.all { resolutionStrategy.cacheChangingModulesFor 0, 'seconds' }
}

Basic Setup

Make sure to have at least the latest version of JDK 1.8 installed. Add to your pom.xml file the following properties:

<properties>
    <kotlin.version>1.5.31</kotlin.version>
    <arrow.version>1.0.1</arrow.version>
</properties>

Add the dependencies that you want to use:

<dependency>
    <groupId>io.arrow-kt</groupId>
    <artifactId>arrow-core</artifactId>
    <version>${arrow.version}</version>
</dependency>

Enabling kapt for the Optics DSL

For the Optics DSL, enable annotation processing using Kotlin plugin:

<plugin>
    <groupId>org.jetbrains.kotlin</groupId>
    <artifactId>kotlin-maven-plugin</artifactId>
    <version>${kotlin.version}</version>
    <executions>
        <execution>
            <id>kapt</id>
            <goals>
                <goal>kapt</goal>
            </goals>
            <configuration>
                <sourceDirs>
                    <sourceDir>src/main/kotlin</sourceDir>
                </sourceDirs>
                <annotationProcessorPaths>
                    <annotationProcessorPath>
                        <groupId>io.arrow-kt</groupId>
                        <artifactId>arrow-meta</artifactId>
                        <version>${arrow.version}</version>
                    </annotationProcessorPath>
                </annotationProcessorPaths>
            </configuration>
        </execution>
        <execution>
            <id>compile</id>
            <phase>compile</phase>
            <goals>
                <goal>compile</goal>
            </goals>
            <configuration>
                <sourceDirs>
                    <sourceDir>src/main/kotlin</sourceDir>
                </sourceDirs>
            </configuration>
        </execution>
        <execution>
            <id>test-compile</id>
            <phase>test-compile</phase>
            <goals>
                <goal>test-compile</goal>
            </goals>
        </execution>
    </executions>
</plugin>

BOM file

To avoid specifying the Arrow version for every dependency, a BOM file is available:

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>io.arrow-kt</groupId>
            <artifactId>arrow-stack</artifactId>
            <version>${arrow.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement><dependencies>
...
</dependencies>

Next development version

If you want to try the latest features, replace 1.0.1 with 1.0.2-SNAPSHOT and add this configuration:

<repository>
    <snapshotss>
        <url>https://oss.sonatype.org/content/repositories/snapshots/</url>
        <updatePolicy>always</updatePolicy>
    </snapshots>
</repository>